1. Field of the Invention
This invention relates to a system for locating a fault, such as malfunction of a repeater or the like, in an optical fiber transmission system in which optical fibers are used as a transmission line and a plurality of optical signal regenerative repeaters are sequentially connected in cascade at predetermined intervals for digital signal transmission.
2. Prior Art
Heretofore, there has been proposed a fault location system providing with a fault monitoring intervence core in a land optical fiber transmission system. In a submarine cable employing optical fibers, however, the use of such an intervence core involves an amplifier for the exclusive use of a monitoring signal, resulting in the defects of enlarged circuit scale of the repeater, increased power dissipation and markedly raised transmission cost.